An inkjet head includes multiple nozzles to eject ink, multiple pressure chambers to apply pressures for the ink to be ejected from the nozzles, and flow paths to supply ink to the pressure chambers etc. If these components of the inkjet head are arranged along a plane (e.g. horizontal plane) perpendicular to the ink ejection direction (e.g. vertical direction), the intervals between the nozzles have to be large, making it impossible to increase the density of ejected ink. An inkjet head has been known where pressure chambers are disposed above nozzles and where a common flow path to supply ink to the pressure chambers is disposed further above the pressure chambers to increase the density (see, for example, Patent Literature 1). Such an inkjet head actuates actuators that are externally in contact with the wall surfaces of the pressure chambers and applies pressures to the interiors of the pressure chambers to eject ink from the nozzles.
FIG. 9 is a cross-sectional view of the configuration, around a nozzle, of a conventional inkjet head.
As shown in FIG. 9, an actuator 203 and a wiring substrate 204 are electrically connected to each other through a bump 205 and a solder 206. The actuator 203 is externally in contact with each pressure chamber 201 through a diaphragm 202 disposed on the upper surface of the pressure chamber 201. The wiring substrate 204 is made of silicon and is disposed above the actuator 203. The bump 205 is formed on an electrode 203a of the actuator 203. The solder 206 is formed on the wiring substrate 204 side. In order to form a space for the bump 205 and the solder 206 between the wiring substrate 204 and the actuator 203, a photopolymer spacer substrate 207 is disposed between a pressure-chamber substrate 201a, which forms the pressure chamber 201, and the wiring substrate 204.